This invention relates to a stationary coil type direct current motor comprising a case made of a magnetic material characterized by a high saturation magnetic flux density and a high permeability and a plurality of coils.
FIG. 9 is a sectional view of a conventional stationary coil type direct current motor. FIG. 10 is a plane view of the conventional stationary coil type direct current motor.
Flanges 5 and 6 are fixed to a case 1. Bearings 7 are fixed to the flange 5 and flange 6. A shaft 4 is supported by the bearings 7. A laminated silicon steel plate 11 is fixed to the inner circumference surface of the case 1. A coil 2 is wound and arranged on the inner circumference surface of the laminated silicon steel plate. A magnet 3 is secured to the shaft 4 and spaced from the coil 2 to define an annular space between the magnet 3 and the coil 2.
However, the conventional direct current motor has the following disadvantages.
1) It is difficult to machine and assemble the laminated silicon steel plate for down sizing of the motor.
2) In view of the construction of the motor, since eliminating the laminated silicon steel plate causes increasing of iron loss of the soft magnetic material forming the magnetic circuit, a motor efficiency will be deteriorated.